Metformin Is Associated with a Lower Incidence of Benign Brain Tumors: A Retrospective Cohort Study in Patients with Type 2 Diabetes Mellitus

Effect of Metformin on Lower Urinary Tract Symptoms in Male Patients with Type 2 Diabetes Mellitus: A Retrospective Cohort Study in Taiwan

PURPOSE

This study investigated the risk of lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH) associated with metformin use.

MATERIALS AND METHODS

We used the database of Taiwan's National Health Insurance to create 9,833 pairs of ever users and never users of metformin matched on propensity score. They were males with a new diagnosis of type 2 diabetes during 1999-2005. The incidence of LUTS/BPH was calculated from January 1, 2006 until December 31, 2011. We estimated hazard ratios by Cox regression weighted on propensity score.

RESULTS

There were 515 incident cases in ever users after a median follow-up of 5.4 years (incidence rate: 11.24 per 1,000 person-years) and 682 cases in never users after 5.2 years (15.92 per 1,000 person-years). The hazard ratio (HR) that compared ever to never users was 0.69 (95% confidence interval [CI], 0.62-0.78). The HRs that compared ever users categorized into quartiles of cumulative duration (<19.33, 19.33-41.56, 41.57-67.17, and >67.17 mo) to never users were 1.02 (0.84-1.23), 1.01 (0.86-1.20), 0.57 (0.47-0.69), and 0.40 (0.32-0.49), respectively. For the quartiles of cumulative dose of <582.00, 582.00-1,361.00, 1,361.01-2,449.00, and >2,449.00 g, the respective HRs were 1.03 (0.85-1.24), 0.96 (0.81-1.13), 0.60 (0.49-0.72), and 0.40 (0.32-0.50). The lower risk was significant in all quartiles of defined daily dose. However, a larger daily dose was associated with a greater risk reduction. There were no significant interactions between metformin and other antidiabetic drugs. Patients who used rosiglitazone and/or pioglitazone without metformin had a significantly higher risk (HR, 1.33; 95% CI, 1.09-1.63) and a combination with metformin attenuated such an adverse impact (HR, 0.78; 95% CI, 0.66-0.91).

CONCLUSIONS

A significantly lower risk of LUTS/BPH is observed in males with type 2 diabetes who use metformin.

Demystifying the Relationship Between Metformin, AMPK, and Doxorubicin Cardiotoxicity

Doxorubicin (DOX) is an extremely effective and wide-spectrum anticancer drug, but its long-term use can lead to heart failure, which presents a serious problem to millions of cancer survivors who have been treated with DOX. Thus, identifying agents that can reduce DOX cardiotoxicity and concurrently enhance its antitumor efficacy would be of great clinical value. In this respect, the classical antidiabetic drug metformin (MET) has stood out, appearing to have both antitumor and cardioprotective properties. MET is proposed to achieve these beneficial effects through the activation of AMP-activated protein kinase (AMPK), an essential regulator of mitochondrial homeostasis and energy metabolism. AMPK itself has been shown to protect the heart and modulate tumor growth under certain conditions. However, the role and mechanism of the hypothesized MET-AMPK axis in DOX cardiotoxicity and antitumor efficacy remain to be firmly established by in vivo studies using tumor-bearing animal models and large-scale prospective clinical trials. This review summarizes currently available literature for or against a role of AMPK in MET-mediated protection against DOX cardiotoxicity. It also highlights the emerging evidence suggesting distinct roles of the AMPK subunit isoforms in mediating the functions of unique AMPK holoenzymes composed of different combinations of isoforms. Moreover, the review provides a perspective regarding future studies that may help fully elucidate the relationship between MET, AMPK and DOX cardiotoxicity.